Many commercially useful microorganisms use glucose as their main carbohydrate source. However, a disadvantage of the use of glucose by microorganisms developed for production of commercially desirable products is the high cost of glucose. The use of sucrose and mixed feedstocks containing sucrose and other sugars as carbohydrate sources for microbial production systems would be more commercially desirable because these materials are usually readily available at a lower cost.
A production microorganism can function more efficiently when it can utilize any sucrose present in a mixed feedstock. Therefore, when a production microorganism does not have the ability to utilize sucrose efficiently as a major carbon source, it cannot operate as efficiently. For example, bacterial cells typically show preferential sugar use, with glucose being the most preferred. In artificial media containing mixtures of sugars, glucose is typically metabolized to its entirety ahead of other sugars. Moreover, many bacteria lack the ability to utilize sucrose. For example, less than 50% of Escherichia coli (E. coli) strains have the ability to utilize sucrose. Thus, when a production microorganism cannot utilize sucrose as a carbohydrate source, it is desirable to engineer the microorganism so that it can utilize sucrose.
Recombinant bacteria that have been engineered to utilize sucrose by incorporation of sucrose utilization genes have been reported. For example, Livshits et al. (U.S. Pat. No. 6,960,455) describe the production of amino acids using Escherichia coli strains containing genes encoding a metabolic pathway for sucrose utilization. Additionally, Olson et al. (Appl. Microbiol. Biotechnol. 74:1031-1040, 2007) describe Escherichia coli strains carrying genes responsible for sucrose degradation, which produce L-tyrosine or L-phenylalanine using sucrose as a carbon source. However, there is a need for bacterial strains that are engineered to utilize sucrose using new sucrose utilization genes and that have an improved ability to utilize sucrose. Additionally, there is a need for bacterial strains that are capable of producing glycerol and glycerol-derived products using sucrose as carbon source.